Light field-driven electron dynamics in 2D-materials

Two dimensional materials such as graphene offer exceptional optical and electronic properties and are therefore predestined for light-field controlled electron dynamics inside of matter. In particular, graphene with its Dirac-cone dispersion relation represents an ideal two-level system where intricately coupled intra-band motion and inter-band (Landau-Zener) electron transitions can be driven under the influence of a strong electric field, i.e., above ~2 V/nm [1] , [2] . Using carrier-envelope phase-controlled few-cycle laser pulses, we have demonstrated such repeated Landau-Zener transitions to be driven fully coherently between valence and conduction band, separated only by half an optical period of 1.3 femtoseconds.